Comparative effectiveness of two adjuvants in antibody production against PLA2 from Crotaluss durissus terrificus venom

Abstract

Antivenoms are produced by immunization of horses with snake venom and adjuvant, usually Freund´s adjuvant. Nevertheless, it is widely known that this procedure induces local and systemic adverse effects. In the present work we evaluate the avidity and neutralizing activity of IgG antibodies against PLA2 from C.d. terrificus venom using two different adjuvant formulations. For this proposal, Balb/c mice were subcutaneously immunized on days 0, 15 and 30 with 10-15μg PLA2/30μg CpG-ODN/Coa-ASC16 or 10-15μg PLA2/Freund´s Adjuvant (complete first and incomplete-booster). On day 50 mice serum was analyzed. Chaotropic agent (KSCN) was used to measure the antigen-antibody binding (relative avidity). The results showed that anti-PLA2 sera obtained by PLA2/CpG-ODN/Coa-ASC16 immunization presented lower avidity than PLA2/Freund´s Adjuvant because 0.75 M KSCN reduced the binding in 79% and 56% respectively, by ELISA assay. On the other hand, neutralization test by using Diheptanoyl Thio-PC (a synthetic chromogenic substrate PLA2) showed similar behavior between both antisera. In summary, CpG-ODN/Coa-ASC16 elicits a humoral response with a lesser avidity that Freund´s adjuvant but a similar neutralizing serum ability. In this way we add knowledge about an alternative innocuous adjuvant to be used on the process of antivenom production.